In respect of objects for measuring structures, an essential aspect is that significant spatial points to be measured are often connected to one another by edges. By way of example, an edge which separates a wall of a room from the ceiling connects two corners of the room. By way of example, if all four corners of the ceiling of a room with a rectangular outline are to be measured, the sighting direction of a structure measuring unit can be changed from a first corner to a next corner by virtue of an edge extending between these corners being tracked.
In the case of simple conventional structure measuring units, a spatial point, e.g. a corner, is sighted manually and the sighting direction is then changed manually to a next spatial point to be measured, e.g. a further corner.
DE 196 48 626 for example discloses a method and a device for measuring an area using a laser ranger with a laser transmitter and a laser receiver. The laser ranger is mounted on a stand. The device furthermore comprises a tilt and rotation apparatus for alignment and direction measuring purposes, a scope and an electronic evaluation unit for detecting angular data and distance data and for transmitting data to a computer. For the purposes of measuring a room, the unit is positioned at a central location in the room, from which all spatial and/or area corners to be detected can be targeted and impinged upon by the laser beam. In accordance with the disclosure of DE 196 48 626, the spatial points to be measured are in this case each targeted individually, optionally with support by observation through a scope in the case of a relatively large distance. Automated sequential measuring of several spatial points, for example for comparison with a scan, is not disclosed in DE 196 48 626. In particular, this document provides no hints whatsoever for options for automatic tracking of edges between adjacent corners to be measured.
A similar device and associated measuring method are disclosed in DE 44 43 413, the complementary laid-open application DE 195 45 589 and in WO 96/18083, which claims the priority of DE 44 43 413. There, a method and a device are described for measuring and marking on distanced lines, areas or in at least partly closed rooms. One or more relevant spatial points are measured in respect of in each case two spatial angles and the distance in relation to a reference point using a laser-distance measuring unit, mounted in a cardan-type mount. The laser-distance measuring unit is pivotable about two mutually perpendicular axes which are equipped with goniometers. In accordance with one embodiment described in these documents, spatial points to be measured are targeted manually, marking points are calculated from the measurement data based on a predetermined relative relationship between measuring and marking, which marking points are then targeted independently by the measuring and marking device.
However, an automatically running functionality for tracking edges, proceeding from merely one defined first spatial point, is not disclosed, and nor is an automated sequential measurement of several spatial points, for example for comparison with a scan.
EP 1 733 185 discloses a device and a method, by means of which, specifically, edges on a polygonal but otherwise planar surface are to be measured exactly. However, an automatically running functionality for tracking edges, proceeding from merely one defined first spatial point, is not disclosed, and nor is an automated sequential measurement of several spatial points.
EP 2 053 353 discloses a reference line-projecting unit with an electro-optical distance measuring unit. In accordance with the teaching of this application document, an optical reference beam, in particular a laser beam, is routed along a defined reference path. In the context of passing along the reference path, there is a distance measurement to at least one point of the reference path by emitting a measurement beam parallel or coaxial to the reference beam or by using the reference beam as measurement beam. After receiving components of the returned measurement beam, a signal is derived from these components and a distance to the at least one point is determined from the signal, wherein the routing along the reference path is repeated at least once and a distance or a distance-related variable is established in each case on each passing through the reference path for the at least one point. Hence, in the case of angle-synchronous distance measurements, the same points are scanned multiple times.
By integrating a distance measuring unit, the system disclosed in EP 2 053 353 also enables a control of the projection on the basis of an established surface topography. In particular, what is disclosed is that, after determining a surface profile, a projection onto a curved surface can be adapted in such a way that distortions due to the curved surface are compensated for and the projection corresponds to the undistorted contour of an object to be measured out or to be marked.
However, nor does EP 2 053 353 disclose or suggest a functionality for, in particular automatic, tracking of edges proceeding from merely one defined, first spatial point.